As well known in the art, a thermal transfer printer refers to a printing device which applies heat to an ink ribbon so that the ink deposited on the ink ribbon is transferred to a printing medium. Thermal transfer printers are categorized into two types: a sublimation type printer which sublimates the ink on the ink ribbon to the printing medium, and a melting type printer which melts wax-based ink to transfer to the printing medium. The sublimation type printer is widely being used for printing identification cards in a company or other organization, while the melting type printer is being used for printing bar codes, labels, and price tags.
FIG. 1 illustrates an example of conventional thermal transfer printers. A ribbon cartridge 4 is detachably installed inside a housing 2, and a paper cassette 20 detachably installed on one side of the printer. The ribbon cartridge 4 is a frame for accommodating ink ribbon 6, and includes a supply reel 8 for winding and providing unused ink ribbon and a take-up reel 10 for withdrawing used ink ribbon. The ink ribbon 6 is comprised of a base layer made of plastic material, and a donor layer deposited on the base layer and including inks of three colors: yellow (Y), magenta (M), and cyan (C), which is activated by heat application. Along the edge of the ink ribbon are printed codes for allowing the printer to identify the colors of the ink.
Above the front end of the paper cassette 20, is installed a feed roller 30 coupled with the upper end of a lever 32 pivotally mounted within the printer housing to permit the upward and downward movement of the feed roller 30. In front of the feed roller 30 are installed a capstan roller 34 and a pinch roller 35 facing each other. Meanwhile, a thermal printing head (TPH) 38 is fixedly installed in front of the feed roller 30. Underneath the thermal printing head 38, is installed a platen roller 40 coupled with the upper end of a lifting lever 42 pivotally mounted within the printer housing to permit the upward and downward movement of the platen roller 40.
When a printing instruction is applied to the printer, the lever 32 rotates clockwise with respect to its bottom hinge and a feed roller 30 rotates clockwise, so that a sheet of paper contacting the feed roller 30 is fed to be pressed between the capstan roller 34 and the pinch roller 36 and transported in the forward direction. The movement of the paper stops just before the paper passes through an exit 44. Afterwards, the lifting lever 42 moves the platen roller 40 upwards to press the ink ribbon 6 and the print paper 12 against the thermal printing head 38. Then, the capstan roller 34, the supply reel 8, and the take-up reel 10 rotates, and heat elements of the thermal printing head 38 applies heat on the ink ribbon, so that the printing of the yellow (Y) color is initiated. When the printing of yellow (Y) color is completed, the platen roller 40 moves downwards and the paper is transported to the left in the figure, so that the printing of magenta (M) and cyan (C) colors are carried out. After the printing of all colors are completed, the platen roller 40 moves downward, the thermal printing head 38 stops heating, the supply reel 8 and the take-up reel 10 stops rotation, and then the printed paper is discharged outside though the exit 44. Thus, the conventional thermal transfer printer implements a full-color image by repeatedly performing three-color frame-sequential recording on the paper.
The conventional thermal transfer printer, however, has a drawback that it needs extensive installation space because the printer requires a paper cassette protruded out of the printer frame. Since the paper experiencing the back-and-forth motion partially gets out of the printer during the three-color frame-sequential recording, extra space should be provided in front of the printer, which further increases the installation space. Meanwhile, the printer necessitates the feed roller and related components for transporting the paper from the paper cassette, which increases the complexity of the printer. On the other hand, if the ribbon supply reel and the take-up reels are installed far apart, both the reels may have to be driven by a complex motive power transmission, which increases the number of the required components. Besides, the separate installation of the ribbon cartridge and the paper cassette is of nuisance, and lowers the user convenience of the printer.
Considering that Internet and digital cameras is popular and the user of the Internet or the digital camera frequently wishes to personally print a downloaded image or a picture taken by the digital camera, the problems of occupying extensive installation space, complex mechanism, and low convenience are impeding the implementation of a small-sized printer facilitating the personal printing of small pictures.